Induction of labor can be
Medically indicated (eg, for preeclampsia Preeclampsia and Eclampsia Preeclampsia is new-onset or worsening of existing hypertension with proteinuria after 20 weeks gestation. Eclampsia is unexplained generalized seizures in patients with preeclampsia. Diagnosis... read more or fetal compromise Fetal Monitoring Labor consists of a series of rhythmic, involuntary or medically induced contractions of the uterus that result in effacement (thinning and shortening) and dilation of the uterine cervix. The... read more )
Elective (to control when delivery occurs)
Before elective induction, gestational age must be determined. Commonly, elective induction has been avoided at 39 weeks because of lack of evidence for perinatal benefit and concern about a higher frequency of cesarean deliveries and other adverse outcomes. This practice may be changing, partly because a 2018 study showed that induction of low-risk women at 39 weeks reduced the frequency of cesarean deliveries (but not perinatal adverse outcomes) compared with expectant management (1 Indications reference Induction of labor is stimulation of uterine contractions before spontaneous labor to achieve vaginal delivery. Induction of labor can be Medically indicated (eg, for preeclampsia or fetal compromise)... read more ).
Contraindications to induction include having or having had the following:
Fundal uterine surgery
Open maternal-fetal surgery (eg, myelomeningocele closure)
Myomectomy involving entry into the uterine cavity
Prior classical (vertical) cesarean incision Technique Cesarean delivery is surgical delivery by incision into the uterus. Up to 30% of deliveries in the US are cesarean. The rate of cesarean delivery fluctuates. It has recently increased, partly... read more in the thickened, muscular portion of the uterus
Placenta previa Placenta Previa Placenta previa is implantation of the placenta over or near the internal os of the cervix. Typically, painless vaginal bleeding with bright red blood occurs after 20 weeks gestation. Diagnosis... read more or vasa previa Vasa Previa Vasa previa occurs when membranes that contain fetal blood vessels connecting the umbilical cord and placenta overlie or are within 2 cm of the internal cervical os. Vasa previa can occur on... read more
Abnormal fetal presentation Fetal Dystocia Fetal dystocia is abnormal fetal size or position resulting in difficult delivery. Diagnosis is by examination, ultrasonography, or response to augmentation of labor. Treatment is with physical... read more (eg, transverse lie, umbilical cord presentation, certain types of fetopelvic disproportion)
Multiple prior uterine scars and breech presentation are relative contraindications.
If the cervix is closed, long, and firm (unfavorable), the goal is to cause the cervix to open and become effaced (favorable). Various pharmacologic or mechanical methods can be used. They include
Misoprostol 25 mcg vaginally every 2 to 4 hours or 25 to 50 mcg orally every 2 hours
Prostaglandin E2 given intracervically (0.5 mg) or as an intravaginal pessary (10 mg [prostaglandins are contraindicated in women with prior cesarean delivery or uterine surgery because these drugs increase the risk of uterine rupture])
Oxytocin in low or high doses
Use of laminaria and transcervical balloon catheters, which may be useful when other methods are ineffective or contraindications exist
Mechanical dilation with a Foley (ie, double-lumen latex) catheter plus misoprostol or oxytocin (1 Technique reference Induction of labor is stimulation of uterine contractions before spontaneous labor to achieve vaginal delivery. Induction of labor can be Medically indicated (eg, for preeclampsia or fetal compromise)... read more )
Once the cervix is favorable, labor is induced.
Constant IV infusion of oxytocin is the most commonly used method; it is safe and cost-effective. Low-dose oxytocin is given at 0.5 to 2 milliunits/minute, increased by 1 to 2 milliunits/minute, usually every 15 to 60 minutes. High-dose oxytocin is given at 6 milliunits/minute, increased by 1 to 6 milliunits/minute every 15 to 40 minutes to a maximum of 40 milliunits/minute. With doses > 40 milliunits/minute, excessive water retention may lead to water intoxication. Use of oxytocin must be supervised to prevent uterine tachysystole (> 5 contractions in 10 minutes averaged over 30 minutes), which may compromise the fetus.
External fetal monitoring Fetal Monitoring Labor consists of a series of rhythmic, involuntary or medically induced contractions of the uterus that result in effacement (thinning and shortening) and dilation of the uterine cervix. The... read more is routine; after amniotomy (deliberate rupture of the membranes), internal monitoring may be indicated if fetal status cannot be assessed externally. Amniotomy can be done to augment labor when the fetal head is applied to a favorable cervix and not ballotable (not floating).